298 MORPHOLOGY OF THE CEREBRAL CONVOLUTIONS. 



change in the nomenclature will be given presently, apart from the fact that it 

 designates this surface in conformity with the name given to the corresponding por- 

 tion of the occipito-temporal. 



Occipitotemporal Lobe (Mesial Surface). 



On this surface may be distinguished two convolutions separated by a single 

 fissure, m.o.t. This fissure is the sulcus occipito-temporalis inferior of Ecker; sul- 

 cus longitudinalis inferior of Huschke, sulcus occipito-temporalis, Pansch; fissura 

 collaterals, Huxley; fissura collateralis or temporalis inferior of Bischoff. I adopt 

 the name given to it by Pansch, prefixing, however, the word mesial, calling it the 

 mesial occipito-temporal fissure, m.o.t. Between this fissure and the fissura occipito- 

 temporalis inferior, ot 2 , on the lateral surface, is a very irregularly developed space 

 or convolution which is the mesial portion of the third or inferior occipito-temporal 

 convolution previously described as found on the lateral surface". Ecker and some 

 other writers, divide this space into two separate convolutions by means of a fissure, 

 which he calls the sulcus temporalis inferior, numbered 13 in fig. 3, PL XXXIV. The 

 convolution lying on the outer or lateral side of this fissure he designates as the 

 third temporal convolution, whilst that on the inner or mesial side of this fissure 

 he calls the gyrus occipito-temporalis lateralis. With this division of Ecker I can- 

 not agree. It is true that a fissure more or less distinct is sometimes found in this 

 place, but when present it is very irregular and constantly bridged over and, as 

 Ecker himself states, it is frequently wanting. It is not found in the brain of the 

 Simiadas except faintly indicated, perhaps, in the Anthropomorpha, and its signifi- 

 cance is entirely secondary and not of primary importance. It is not even men- 

 tioned b}^ Pansch, and must be considered of doubtful constancy and compounded 

 of important sulculi merely marking the meso-inferior portion of the third occipito- 

 frontal convolution. This convolution should not, therefore, be divided into two. 

 In the greater number of brains examined, I have found no indication at all of a dis- 

 tinct fissure dividing this convolution, and in those few brains where I have observed 

 it, it has been short and frequently interrupted. Ecker also remarks in connection 

 with this point as follows : " Sometimes in this space (the space between the first 

 temporal and the mesial occipito-temporal fissure) there are two fissures distinguish- 

 able, more or less parallel with the above named, by which three convolutions are 

 marked ; at other times only one fissure is to be recognized and of course only two 

 convolutions." 



Between the mesial occipito-temporal fissure on the one hand, and the calcarine 

 and lower branch of the mesial arched or hippocampal, hp, on the other, is a long, 

 continuous convolution, M.O.T. in PI. XLII, fig. 2 and PI. XLIV, fig. 2, extending 

 from the occipital lobe, 0, to the anterior extremity of the temporal. This I will 

 term the mesial occipito-temporal convolution (gyrus occipito-temporalis medialis) 

 following Ecker and Pansch. Different writers have separated this single convolu- 

 tion into two or more separate and distinct ones. By including it as a whole under 

 one name, and then, merely for purpose of description and location, designating 



